Prior clutch mechanisms for temporarily coupling a continuously rotating drive to an output have taken many forms including mechanically actuated closures of spring-biased face plates, electromagnetically actuated clutches, pawl and ratchet combinations and so forth. Such devices maintain the coupling of power as long as the actuating signal or force is present. Various uses of such clutches require less than continuous coupling of input to output and automatic clutch disengagement after a predetermined amount of rotary output is produced. A particular need for such devices is in applications wherein coupling of a single revolution of rotary input power to an output device is needed.
One example of a single revolution clutch in the prior art is an arrangement wherein a pawl on one member engages a ratchet on the other and is initiated by an actuation movement to start the rotation with release of the pawl at the end of one revolution by a stop mechanism. For instance, the June 1964 IBM Technical Disclosure Bulletin (Vol. 7, No. 1) at pages 89-90 in the article entitled "Non-Searching One Revolution Clutch" by H. Reichle shows such a pawl and ratchet combination wherein the pawl is normally biased by a spring into the engagement direction but an intercepting shoulder configuration releases the pawl after each single revolution. Movement of the intercepting shoulders initiates coupling by releasing the pawl for engagement.
Yet another version of a single revolution clutch is shown in U.S. Pat. No. 2,626,028 by Brougher wherein an inner member with an arcuate groove including a stub wedge continuously rotates from the primary power source. A pin is biased inwardly through a ring into the groove except when cam faces and rollers force the shaft on which the pin is mounted in an outward direction so that the pin is retracted from the groove and held in an extended position. While the pin is within the groove, the stub wedge engages the pin and rotates the ring with the innerdriven member.
The prior art self-contained clutches are all relatively complex in manufacture and operation and suffer varying degrees of reliability loss because of the various moving elements required. In addition, relatively intricate fabrication processes are required, further increasing the manufacturing cost of such single revolution clutches.